The present invention relates generally to an improved gas turbine engine design and, in particular, to an improved core system which replaces the high pressure system of conventional gas turbine engines A booster compressor of the gas turbine engine is utilized in a manner so as to mitigate various effects of such improved core system and thereby retain a conventional low pressure turbine design.
It is well known that typical gas turbine engines are based on the ideal Brayton Cycle, where air is compressed adiabatically, heat is added at constant pressure, the resulting hot gas is expanded in a turbine, and heat is rejected at constant pressure. The energy above that required to drive the compression system is then available for propulsion or other work. Such gas turbine engines generally rely upon deflagrative combustion to burn a fuel/air mixture and produce combustion gas products which travel at relatively slow rates and relatively constant pressure within a combustion chamber. While engines based on the Brayton Cycle have reached a high level of thermodynamic efficiency by steady improvements in component efficiencies and increases in pressure ratio and peak temperature, further improvements are becoming increasingly more difficult to obtain.
Although the combustors utilized in the conventional gas turbine engine are the type where pressure therein is maintained substantially constant, improvements in engine cycle performance and efficiency have been obtained by operating the engine so that the combustion occurs as a detonation in either a continuous or pulsed mode. Several pulse detonation system designs, for example, have been disclosed by the assignee of the present invention in the following patent applications: (1) “Pulse Detonation Device For A Gas Turbine Engine,” having Ser. No. 10/383,027; (2) “Pulse Detonation System For A Gas Turbine Engine,” having Ser. No. 10/405,561; (3) “Integral Pulse Detonation System For A Gas Turbine Engine” having Ser. No. 10/418,859; (4) “Rotating Pulse Detonation System For A Gas Turbine Engine” having Ser. No. 10/422,314; and, (5) “Rotary Pulse Detonation System With Aerodynamic Detonation Passages For Use In A Gas Turbine Engine” having Ser. No. 10/803,293.
It will be appreciated that a pulse detonation device produces pulses of hot gas that are of approximately the same pressure. Time averaged pressure of such pulses is similar in magnitude to the pressure generated in a typical low pressure turbine engine, but at a higher temperature than normally associated with the low pressure turbine engine. It will be understood that a constant volume combustor similarly produces pulses of high-pressure, high-temperature gas that can also be utilized in the pulse detonation type of arrangement. An example of a stationary constant volume combustor is disclosed in U.S. Pat. No. 3,877,219 to Hagen, while a constant volume combustor including a rotatable element is disclosed in U.S. Pat. No. 5,960,625 to Zdvorak, Sr.
In this way, the core or high pressure system of the conventional gas turbine engine may be replaced with a more efficient and less complicated system involving primarily the combustor. At the same time, the modified gas turbine engine will be able to retain the conventional low pressure turbine, as well as the conventional operability characteristics thereof.
Accordingly, it would be desirable for a practical overall architecture be developed for a gas turbine engine utilizing a pulse detonation device or a constant volume combustor in the core system to further improve overall engine efficiency. Further, it would be desirable for such architecture to incorporate a cooling system and method which mitigates the pulsing nature of the combustion discharge and reduces engine noise.